Production of titanium tetrachloride



United States Patent- PRODUCTION OF TITANIUM TETRACHLORIDE Howard M. Cyrand Frank S. Grifiith, Palmerton, and Charles lVL'McFarland, Lehighton,Pa., assignors to The New Jersey Zinc Company, New York, N. Y., acorporation of New Jersey No Drawing. Application July 26, 1955, SerialNo. 524,614

2 Claims. (Cl. 2387) This invention relates to the production oftitanium tetrachloride and, more particularly, to the production oftitanium tetrachloride from titaniferous raw materials by a continuousand autogenous chlorination process.

Years of research have been expended on the problem of producingtitanium tetrachloride by the chlorination of titaniferous material suchas ilmenite. The early' chlorination procedures favored the use offinely divided titaniferous material and carbon in order to permitaccess of chlorine gas to the solid components of the reaction mass. Butit was found that even a finely divided mass of titaniferous materialand carbon was not readily penetrable by the chlorine, so L. E. Bartonproposed, as described in his United States Patent No. 1,179,394, theuse of a large amount of coking coal as the source of carbon and thecoking of an uncompressed mixture of this coal and titaniferous materialin order to form a porous cinder. This cinder was sufliciently porous topromote greater access of the chlorine to the titaniferous material whenthe chlorination was carried out in the then-conventional chlorinationapparatus which, as pointed out by Barton, usually consisted of amultiplicity of horizontal trays in Whichthe solid reactants were heatedto redness. The amount of carbon used by Barton was sufliciently greatto permit the cinder to retain its original form and structure evenafter substantially complete exhaustion of its original titaniumcomponent. More recently, I. E. Muskat et al., in their United StatesPatent No. 2,184,887, pointed out that the chlorination of titaniferousmaterial in admixture with carbon could be carried out without use ofexternal heating, i. e. autogenously, by using not more than about 35%of carbon by weight of the titaniferous material. Muskat et al. furtherfound that such a mixture of titaniferous material and carbon could bechlorinated autogenously in briquetted form, but, they pointed out anincrease in carbon content beyond their 35% limit exerted a quenchingeifect upon the chlorination reaction, thus making temperaturemaintenance very difficult. Unlike the Barton cinder, the Muskat et al.briquettes, asthey are chlorinated, disintegrate into an ash which iswithdrawn from the chlorinating furnace.

The Barton procedure is one in which the cinder, resembling What is nowknown as coke fingers, is relatively immovable in the chlorinatingreaction zone because of the interlocking of the sharp-edged fingers.Accordingly, the Barton cinder resists moving or settling through achlorination zone, and consequently the Barton procedure is normally abatch operation. Experience has shown, as described on page 735 of theJune 1954 issue of the Journal of Metals, in the article entitledTitanium metal production expanded at Henderson plant, and on page 86 ofthe March 19, 1955, issue of Chemical Week, in the article entitledFluid route bypasses problems, that the type of operation proposed byMuskat et al. is interrupted by the accumulation of fine ash in thebottom of the chlorinating furnace and is therefore discontinuous.

ICC

Contrary to Bartons teaching that the mixture of titaniferous materialwith a large amount of carbon should be uncompressed in order that it beporous and penetrable by chlorine, and contrary to the Muskat et al.statement that amounts of carbon in excess of about 35% by weight of thetitaniferous material quench the chlorination reaction so as to make itdifiicult or impossible to maintain autogenous reaction conditions, wehave discovered that a densified, briquetted mixture of titaniferousmaterial and at least by weight of at least partially cokablecarbonaceous material canbe chlorinated under completely autogenousreaction conditions and, moreover, that this autogenous reaction can bemaintained under continuous operating conditions wherein the briquettesare charged to one end of the chlorinating zone and the resultingtitanium-depleted briquettes are withdrawn from the other end of thechlorinating zone without significant interruption of the chlorinationreaction. I e

The method of our present invention is therefore directed to thecontinuous and autogenous chlorination of the titanium component oftitaniferous material containing at least 20% titanium oxide calculatedas TiOz, and comprises initially preparing a charge consistingessentially of the aforesaid titaniferous material and solidcarbonaceous material, both in finely divided form, in which thecarbonaceous material contains about 50% to coking coal and the balance,if any, non-coking coal. The total amount of this carbonaceous materialadmixed with the titaniferous material ranges from about 75% to byWeight of the titaniferous material. This charge is then simultaneouslymixed and compressed to eifect intimate contact. between thetitaniferous and carbonaceous materials. Thereafter, the mixture isbriquetted. The density of the briquette is at least 25% and usually 70%greater than the bulk density of the original mix. The briquettedmixture is coked at a temperature. of at least about 600 C. for a periodof time sufficient to drive oif substantially all of those volatilecomponents of the coking coal which can be evolved at that temperature.The resulting coked briquettes are charged to one end of a chlorinatingzone. Chlorine gas is passed substantially continuously through a bodyof the coked briquettes which are maintained at a chlorination reactiontemperature within the range of about 600 to 1000 C. by the exothermicheat of the chlorination reaction resulting from contact between thechlorine gas and the hot briquettes. The chlorination of the titaniumcomponent of the briquettes is thus eifected without substantiallydestroying the coherent structure of the briquettes and While permittingthe briquettes to move substantially continuously through thechlorinating zone from the charging end thereof toward a. discharge endof said zone as their titanium content is being depleted bychlorination. The titanium-depleted briquettes are withdrawn from thedischarge end of the chlorinating zone while the chlorination reactionis continued, whereby an uninterrupted autogenous reaction in thechlorinating zone is maintained. The titanium tetrachloride evolved inthe chlorinating zone is recovered by conventional means. Although wehave found that when relatively small cold briquettes are delivereddirectly to the reactor, the heat generated by the chlorination reactionis sufficient to maintain autogenous chlorinating conditions, theconservation of heat by charging the coked briquettes while still hotincreases the length of the chlorination reaction period while thebriquettes pass through the reactor and thus promotes substantiallycomplete chlorination of even the largest briquettes.

The titaniferous material which may be chlorinated by the method of ourinvention includes titanium ores and titanium concentrates. For example,rutile and ilmenite are representative of such titanium ores and theslags produced as described in United States Patent No. 2,476,453' arerepresentative of titanium concentrates which may be'used in practicingour invention. Ilmenites generally contain from about to or more oftitanium dioxide (with an iron oxide content which is generally greaterwith lower titanium oxide contents), and native rutiles contain as highas 95% titanium dioxide (and generally nearly free of iron oxide). Theaforementioned slag concentrates contain at least and generally at least70%, titanium oxide calculated as TiOz. These slag concentrates furthercontain varying amounts of iron oxide up to 20%, calculated as Fe. andmay contain up to 18% of lime and magnesia calculated as CaO and MgO. Ingeneral, slag concentrates containing amounts of iron oxide approachingthe aforesaid upper limit of 20% contain relatively small amounts oflime, and conversely the slag concentrates containing amounts of limeapproaching the upper limit of 18% are generally characterized by thepresence of only a small amount of iron oxide. Although either of thesetwo extremes of slag concentrate composition as well as compositions ofintermediate iron oxide and lime contents may be used in practicing ourinvention, the method of our invention is of particular value in thechlorination of those slag concentrates which are relatively low in ironoxide and relatively high in lime. The lime and magnesia present asgangue constituents in titanium slag concentrates become chlorinated tosome extent and the resulting calcium and magnesium chlorides form meltswhich have lower freezing points than either of the individualchlorides. Thus, these chlorides tend to form a liquid mixture at thenormal operating temperature in the practice of our invention, but theporosity of our briquettc structure is such that this melt is largelyadsorbed and is to this extent sequestered by the briquettes so as notto interfere with the chlorination of the titaniferous material.Moreover, this sequestering of the molten calcium and magnesiumchlorides precludes the possibility of the briquettes being stucktogether by an outer film or coating of the molten chlorides.

The solid carbonaceous material with which the titaniferous material ismixed in practicing our invention is characterized by the presence ofcoking coal either with or without a minor amount of non-coking coal.The presence of the coking coal promotes the development of structuralstability'in the resulting coked briquettes by virtue of the fusion (andhence binding eifect) of the coking coal during the coking operation. Inorder to assure this result, we have found it advantageous to use coking(bituminous) coals of high fluidity, that is, coals having a fluidity ofabout 10,000 units or more on the Giesler fluidity scale (a plastometrictest procedure described in Appendix III of the A. S. T. M. Standards onCoal and Coke, 1948). In general, we have found that the carbonaceousmaterial should comprise at least about 50% by weight of coking coal andmay consist exclusively of such coking coal. If less than all of thecarbonaceous material is provided in the form of coking coal, thebalance may be provided by the use of noncoking coal,such as anthracite,coke breeze or petroleum coke, or mixtures of these substantiallynon-coking coals (as they are referred to collectively herein and in theclaims).

The amount of such carbonaceous material admixed with the titaniferousmaterial in the practice of our invention ranges between 75% and 135% byweight of the titaniferous material. In the case of ilmenites,regardless of their titanium oxide content, the same range ofcarbonaceous material is required because, when the titanium oxidecontent of the ilmenite is relatively low, its iron oxide content isrelatively high and the chlorination of this iron consumes aconsiderable amount of available carbon. The aforementioned titaniumslag concentrates correspond to a relatively high titanium oxideilmenite and thus require the same amount of carbonaceous material forchlorination. In the case of rutile, the same range of carbonaceousmaterial is required for chlorination of the high titanium oxide contentof the rutile. Amounts of carbonaceous material below about do not formcoked briquettes containing an adequate residual structure to supportthe briquettes after substantially all of the titanium component of thetitaniferous material (regardless of its nature) has been chlorinated.Amounts of carbonaceous material above the upper limit of theaforementioned range may be used but tend to lower the capacity of thefurnace. Therefore, the aforementioned range for'the proportion ofcarbonaceous material to titaniferous material represents the mostadvantageous condition for obtaining a coked briquette having theoptimum combination of structural stability, ability to absorb moltenresidual chlorides and accessibility of the titanium for chlorination.

Both the titaniferous material and the coking coal component of thecarbonaceous material should be finely divided inasmuch as a fine degreeof subdivision of the titaniferous material promotes its chlorinationand a fine degree of subdivision of the coking coal contributessignificantly to the formation of structurally stable briquettes. Thus,both of these components should be ground to all minus 20 mesh (TylerStandard) and 30% minus 200 mesh either separately before mixing ortogether after mixing. However, we have found it advantageous to use thenon-coking component'of the carbonaceous material in a coarsercondition, nominally through 6 and on mesh.

The titaniferous material and carbonaceous material are brought intointimate contact with one another by a mixing and compression treatmentwhich can be readily achieved in a pug mill or in the type of deviceknown as an edge runner, chaser or Chilean mill. The resulting mixtureforms a more coherent and stable briquette structure which, aftercoking, is nevertheless sufficiently porous to promote effectivechlorination of its titaniferous component.

The resulting intimate mixture of titaniferous material and solidcarbonaceous material is then briquetted. For this purpose, moisteningwith water will produce a sufficiently plastic and coherent mass toretain a subsequently applied briquetted shape. However, in order toimpart greater structural strength to the uncoked briquette, we havefound it advantageous to introduce a small amount, generally about 3 to8% by weight, of a carbonaceous binding agent such as sulfite liquor,pitch, or the like, as distinguished from argillaceous binders, such asbentonite and other clays, which tend to impair the porosity of theresultingbriquettes and also introduce impurities into the titaniumtetrachloride. Conventional briquetting equipment, such for example asthat which forms pillow-block briquettes 2 inches by 2 inches by 1%inches, will produce from such moistened mixtures briquettes havingadequate strength to withstand subsequent coking.

Coking of the briquetted mixture may be carried out In general, coking abody of the coked briquettes while maintaining the.

briquettes at a temperature advantageously within the range of 600 to1000 C. Within this temperature range, the chlorine readily permeatesthe briquette structure and reacts with the titanium oxide component ofthe titaniferous material with the resulting formation of titaniumtetrachloride vapor as the primary product and carbon monoxide andcarbon dioxide as the main by-products. In addition, the chlorine reactswith the iron, magnesium, calcium, aluminum and silicon oxides tovarying extents depending upon the temperature and composition of thebriquettes. After the chlorination reaction has been initiated, theexothermic heat of reaction is sufiicient to maintain the chlorinationtemperature range without the application of external heat. Thus,completely autogenous reaction conditions prevail in the practice of ourinvention. The chlorine gas is substantially continuously passed throughthe body of coked briquettes which are maintained at reactiontemperature by the exothermic heat of reaction, and the coked briquettescharged to one end of the chlorination reaction zone move substantiallycontinuously through and toward a discharge end of the chlorinating zoneas their titanium content is being depleted by chlorination. Thetitanium-depleted briquettes are withdrawn from the discharge end of thechlorinating zone in such manner as to maintain uninterrupted autogenousreaction conditions in the chlorinating zone; that is, thetitanium-depleted briquettes are withdrawn either continuously orintermittently, but in either event they are withdrawn at an averagerate substantially equal to the rate at which they are produced by thechlorination reaction. Thus, by substantially continuously passingchlorine gas through the body of hot titanium-containing briquettes inthe reaction zone, and by charging fresh briquettes to one end of thiszone and discharging spent 1.6 before, the briquettes of our inventionpromote a degree of selectivity in the chlorination of the titaniferousslag concentrate which has not been achievable heretofore. Moreover, thefact that these briquettes make it possible to chlorinate the charge inthe form of a long slender column works to the advantage of our methodinasmuch as a slender reaction column eifectively radiates theexothermic heat of reaction and promotes substantially uniformtemperatures throughout the cross section of the column. Actual controlof the reaction temperature may be achieved by various expedients, suchas by dilution of the chlorine with an inert gas, by dilution of thebriquettes with non-reactive materials, by spreading or contracting thereaction zone by increasing or decreasing the size of the ore or slagparticles, by varying the size of the briquettes, by diffusion of thedistribution of the chlorine in the reactor (i. e., by introducing itinto vertically spaced portions of the briquette charge), by varying therates of charging the briquettes and chlorine, by varying the relativeproportions of preheated and cold briquettes in the charge, by choice offurnace insulation, or by a combination of these expedients. Theresulting facility for Titanium Source Coking Coal Non-Coking CoalBinder Sorel Slag Bituminous Goal 1 Metallurgical Coke Sulfite LiquorComp. Percent Comp. Percent Comp. Percent Comp. Percent 70. Volatile.37. 1 Fixed 0... Fixed 0... 54. 2 Ash Ash .i

High fluidity coal, Giesler fluidometer rating to 14,000 R. P. M.compared with very low R. P. M. for coals used in metallurgical coke.

briquettes from the other end of the reaction zone, sub stantiallycontinuous chlorination of the titanium-containing briquettes isachieved without interruption in the autogenous reaction conditionswhich prevail in the chlorination reaction zone.

Inasmuch as the degree of reactivity of the magnesium, aluminum andsilicon components of the briquettes increases with the chlorinationtemperature, there is an economic advantage in conducting the reactionat a temperature sufiiciently high to effect chlorination of thetitanium while sufliciently low to minify chlorination of the othercomponents of the briquettes. The high structural strength of thebriquettes of our invention makes possible their chlorination in a deepbut narrow bed, as in a long slender column, and the resulting deep bedofiers a longer reaction period for the ascending chlorine. Thisprolonged reaction opportunity permits the use of a lower chlorinationtemperature while nevertheless insuring complete chlorination reaction.Inasmuch as lower reaction temperatures minify the chlorination of thenon-titaniferous components of the charge as pointed out herein- A mixcomposed of 50 parts of the slag, 40 parts of the bituminous coal, 10parts of the coke, 7 parts of the binder, and water as required, wasblended and had a bulk density of about 55 pounds per cubic foot. The

lended mixture wasthcn treated in a Chilean type mill (also known as achaser). The mix was discharged from the chaser and briquetted on acommercially available roll press which form 2" by 2" by 1%" pillowblock briquettes with a density of about pounds per cubic foot measuredby determining the volume displaced by a briquette of known weight.These briquettes were broken inhalf for a more effective size in thesubsequent chlorination operation. These briquettes were placed in asteam dryer for 2 hours to eliminate moisture which would otherwisecause them to crack badly in the heat of the coking furnace. The driedbriquettes were hard and could be handled without breakage.

The dried briquettes were then coked at 900 C. for 1 hour. During thecoking most of the volatile matter in the coal and the binder was drivenoh, and the resulting hard coke structure had the following analysis.

7 TiOa 45.8% FeO 7.2 CaO 1.7 MgO 4.0 SiOz 5.7 A1203 6.1 Bulk density 44lb./cu.ft. Apparent briquette density 90 lb./cu.ft. 1 ilriquetteporosity 40% Measured by determining the volume displaced by a hriquetteof known weight.

For the chlorination operation, a vertically disposed retort was filledto a depth of 2 ft. with lump coal (although it has been found that cokeor residue briquettes from a previous chlorination operation couldsimilarly be used), and then hot briquettes coked as describedhereinbefore were added to a depth totaling 7 ft. (approximately 160 lb.of the hot briquettes were used for this change). Air was introducednear the bottom of the retort at the rate of about 50 cubic feet perminute in order to burn the coal and preheat the retort. When thethermocouples inside the retort recorded about 700 C. (and thistemperature was attained in about 1 /2 hrs.), the air supply was turnedoff. The burning coal charge was quickly lowered in the retort and thehot coked slag briquettes were charged at the top to bring the chargelevel above the gas exit level at which the effiuent gases werewithdrawn '(at a height about '8 feet above the bottom of the retort).

Chlorine was then introduced into the bottom of the retort at a flowrate of 5 to 6 cubic feet per minute, and thereafter the chlorinationreaction proceeded autogenously. Thereafter, hot coked briquettes werecharged intermittently to the retort at a rate of 60 pounds an hour.These charging rates provided an excess of chlorine to insure theformation of FCl3 which is more volatile than FeClz while neverthelessholding the excess chlorine in the exit gas to 2% or less. A reactionzone temperature of 800 C. to 900 C. was maintained autogenously by theheat of the chlorination reaction in the retort, and the chloridesvolatile at these temperatures, to wit, SiC14, TiCh, FeCls, and AlCls,were withdrawn from the retort through the efiiuent gas outlet along.with CO and C02. The vapors were cooled with a jet of cold TiCl4 andthe resultant titanium tetrachloride slurry was collected in a storagetank. The less volatile CaClz and MgClz remained in the residuebriquettes which were discharged from the retort at regular intervals.The charge of'briquettes kept their shape and did not form excessivefines in spite of the fact that they moved progressively downwardlythrough the retort as their titanium content was being depleted by thechlorination reaction. The downward movement of the body of briquettesthrough the chlorinating zone was efiected by intermittently dischargingthe spent briquettes through a star valve at the lower end of the retortat a rate sufiicient to make room in the upper portion of the retort forthe charge of fresh briquettes. in spite of this discharging of spentbriquettes from the chlorinating retort, the delivery of chlorine gas tothe retort was continued so as to maintain the autogenous reactionconditions prevailing within the retort.

it should be noted that temperature control for the chlorinationoperation was achieved simply by adjusting the sensible heat in thecoked briquettes charged to the retort. in the operation describedherein, the chlorination reaction zone temperature of 800-900 C. wasmaintained by charging approximately half of the briquettes directlyfrom the coking operation and the other half in the form of cokedbriquettes which had cooled to ambient temperature.

The aforementioned titanium tetrachloride-containing slurry was red incolor, clue to the presence of solid iron chlorides in the liquidtitanium tetrachloride, but after filtering this slurry the resultingliquid phase comprised a clear straw-yellow liquor, Removal of thevanadium c 8 content of this liquor by conventional procedure and itssubsequent distillation resulted in a water-white liquid titaniumtetrachloride of high degree of purity and suitable for use as a rawmaterial from which ductile metallic titanium was produced.

It will be seen, accordingly, that the method, of our invention makespossible the effective and substantially complete chlorination of thetitanium component of titaniferous materials of natural or artificialorigin in a continuous and autogenous operation. The residual coherentbriquette structure which is obtained as chlorination of the titaniumcomponent of the briquettes nears completion maintains a uniformphysical distribution of the titanium component in the chlorinatingatmosphere and thus assures substantially complete utilization of thetitaniferous value of the starting material as well as continuity of thechlorination operation without interruption for the discharge of spentcharge.

This is a continuation-in-part of our copending application Serial No.504,124, filed April 26, 1955, which in turn was a continuation-in-partof our then pending application Serial No. 408,293, filed February 4,1954, both applications Serial No. 504,134 and Serial No. 408,293aforementioned having now been abandoned.

We claim:

1. The method of continuously and autogcnously chlorinating the titaniumcomponent of titaniferous material which comprises preparing a chargeconsisting essentially of finely divided titaniferous material and solidcarbonaceous material, the titaniferous material containing at least 20%titanium oxide calculated as TiOz and the carbonaceous materialcontaining about to 100% by weight of coking coal and the balanceessentially non-coking coal, the total amount of said carbonaceousmaterial ranging between about 75% and 135% by weight of thetitaniferous material so as to provide a substantial carbonaceousresidue after chlorination of the titanium content of the titaniferousmaterial in contact therewith, simultaneously mixing and compressing thecharge of said titaniferous material and carbonaceous material to effectintimate contact between these materials, thereafter forming briquetteshaving a density at least 25% higher than that of the charge, coking thebriquettes at a temperature of at least about 600 C., charging the cokedbriquettes to one end of a chlorinating zone, passing chlorine gassubstantially continuously through a body of the coked briquettes,maintaining said body of coked briquettes at a chlorination reactiontemperature within the range of about 600 to 1000 C. by the exothermicheat of the chlorination reaction resulting from the contact between thechlorine gas and the hot briquettes, the chlorination of the tita niumcomponent of the briquettes thus being effected without substantiallydestroying the coherent structure of said briquettes and whilepermitting the briquettes to move substantially continuously through thechlorinating zone from the charging end thereof toward a discharge endof said zone as their titanium content is being depleted bychlorination, withdrawing titaniumdepleted briquettes from the dischargeend of the chlorinating zone while the chlorination reaction iscontinuing whereby uninterrupted autogenous reaction in the chlorinatingzone is maintained, and recovering the resulting titanium tetrachlorideevolved in the chlorinating zone.

2. The method of continuously and autogenously chlorinating the titaniumcomponent of titanium slag concentrate containing at least titaniumoxide calculated as TiOz, up to 20% iron oxide calculated as Fe, and upto 18% lime calculated as CaO, which comprises preparing a chargeconsisting essentially of said slag and solid carbonaceous material bothin finely divided form, said carbonaceous material containing about 50%to 100% by weight of coking coal and the balance essentially non-cokingcoal, the total amount of said carbtmaceous material ranging betweenabout and 135% by weight of the slag concentrate so as to provide asubstantial carbonaceous residue after chlorination of the titaniumcontent of the slag concentrate in contact therewith, simultaneouslymixing and compressing the charge of said slag concentrate andcarbonaceous material to eifect intimate contact between thesematerials, thereafter forming briquettes having a density at least 25%higher than that of the charge, coking the briquettes at a temperatureof at least about 600 C., charging the coked briquettes to one end of achlorinating zone, passing chlorine gas substantially continuouslythrough a body of the coked briquettes, maintaining said body of cokedbriquettes at a chlorination reaction temperature within the range ofabout 600 to 1000 C. by the exothermic heat of the chlorination reactionresulting from the contact between the chlorine gas andthe hotbriquettes,

the chlorination of the titanium component of the briquettes thus beingeffected without substantially destroying the coherent structure of saidbriquettes and while permitting the briquettes to move substantiallycontinuously through the chlorinating zone from the charging end thereoftoward a discharge end of said zone as their titanium content is beingdepleted by chlorination, withdrawing titanium-depleted briquettes fromthe discharge end of the chlorinating zone while the chlorinationreaction is continued whereby uninterrupted autogenous reaction in thechlorinating zone is maintained,'and recovering the resulting titaniumtetrachloride evolved in the chlorinating zone.

No references cited.

1. THE METHOD OF CONTINUOUSLY AND AUTOGENOUSLY CHLORINATING THE TITANIUMCOMPONENT OF TITANIFEROUS MATERIAL WHICH COMPRISES PREPARING A CHARGECONSISTING ESSENTIALLY OF FINELY DIVIDED TITANIFEROUS MATERIAL AND SOLIDCARBONACEOUS MATERIAL, THE TITANIFEROUS MATERIAL CONTAINING AT LEAST 20%TITANIUM OXIDE CALCULATED AS TIO2 AND THE CARBONACEOUS MATERIALCONTAINING ABOUT 50% TO 100% BY WEIGHT OF COKING COAL AND THE BALANCEESSENTIALLY NON-COKING COAL, THE TOTAL AMOUNT OF SAID CARBONACEOUSMATERIAL RANGING BETWEEN ABOUT 75% AND 135% BY WEIGHT OF THETITANIFEROUS MATERIAL SO AS TO PROVIDE A SUBSTANTIAL CARBONACEOUSRESIDUE AFTER CHLORINATION OF THE TITANIUM CONTENT OF THETITANIFEROUSMATERIAL IN CONTACT THEREWITH, SIMULTANEOUSLY MIXING AND COMPRESSING THECHARGE OF SAID TITANIFEROUS MATERIAL AND CARBONACEOUS MATERIAL TO EFFECTINTIMATE CONTACT BETWEEN THESE MATERIALS, THEREAFTER FORMING BRIQUETTESHAVING A DENSITY AT LEAST 25% HIGHER THAN THAT OF THE CHARGE, COKING THEBRIQUETTES AT A TEMPERATURE OF AT LEAST ABOUT 600*C., CHARGING THE COKEDBRIQUETTES TO ONE END OF A CHLORINATING ZONE, PASSING CHLORINE GASSUBSTANTIALLY CONTINUOUSLY THROUGH A BODY OF THE COKED BRIQUETTES,MAINTAINING SAID BODY OF COKED BRIQUETTES AT A CHLORINATION REACTIONTEMPERATURE WITHIN THE RANGE OF ABOUT 600* TO 1000* C. BY THE EXOTHERMICHEAT OF THE CHLORINATION REACTION RESULTING FROM THE CONTACT BETWEEN THECHLORINE GAS AND THE HOT BRIQUETTES, THE CHLORINATION OF THE TITANIUMCOMPONENT OF THE BRIQUETTES THUS BEING EFFECTED WITHOUT SUBSTANTIALLYDESTROYING THE COHERENT STRUCTURE OF SAID BRIQUETTES AND WHILEPERMITTING THE BRIQUETTES TO MOVE SUBSTANTIALLY CONTINUOUSLY THROUGH THECHLORINATING ZONE FROM THE CHARGING END THEREOF TOWARD A DISCHARGE ENDOF SAID ZONE AS THEIR TITANIUM CONTENT IS BEING DEPLETED BYCHLORINATION, WITHDRAWING TITANIUMDEPLETED BRIQUETTES FROM THE DISCHARGEEND OF THE CHLORINATING ZONE WHILE THE CHLORINATION REACTION ISCONTINUING WHEREBY UNINTERRUPTED AUTOGENOUS REACTION IN THE CHLORINATINGZONE IS MAINTAINED, AND RECOVERING THE RESULTING TITANIUM TETRACHLORIDEEVOLVED IN THE CHLORINATING ZONE.